Earlier quoted context omitted.
No need to panic. Just because the video has high production values doesn't mean it's an accurate prediction of the future, or that effective countermeasures won't be found.
I’m gonna have to say I disagree. We are already making tiny drones the size of bees. And you don’t need that size to make a reliable, one shot bomb to kill someone. Anyone with time, a bit of money, and a plan can make a swarm of drones to fly into a crowd automatically and blow themselves up remotely. The fact that I hasn’t happened already just surprises me.
The real fact is that there aren't that many evil genius terrorists plotting a way to kill a crowd of people.
To me, the worry about killbots is state actors, not terrorists. Countries aren't usually about indiscriminate murder, they're usually trying to scythe away one group... Picking people out of a crowd and murdering them with facial recognition drones is a more realistic fear, imho.